In thin film transistors, high electric fields may be formed near the drain, resulting in impact ionization, which increases the drain current. This phenomenon is called the kink effect. National Publication of Translation No. 2003-519917 (WO01/050514) describes a technique of reducing such kink effect.
The above gazette discloses the technique of splitting the gate electrode into a plurality of portions so that carriers are absorbed into a silicon layer between the split portions of the gate electrode, to thereby suppress the kink effect.
The kink effect is indeed suppressed by splitting a gate electrode into a plurality of portions and providing a silicon layer between the split portions of the gate electrode as described in the above gazette; however, the saturation current which affects the quality of analog circuit characteristics is still large. Such increase in saturation current is generally called the channel length modulation effect.